Methods of treatment of hot rolled rod



F. KOCKS METHODS OF TREATMENT OF no'r ROLLED ROD Filed June 24, 1966 INVENTOR Friedrich Kocks United States Patent 3,484,310 METHODS OF TREATMENT OF HOT ROLLED ROD Friedrich Kocks, Dusseldorf, Germany, assignor to Kommanditgesellschaft Friedrich Kocks, Dusseldorf, Germany, a corporation of Germany Filed June 24, 1966, Ser. No. 560,203 Int. Cl. C21d 1/06 US. Cl. 148153 4 Claims ABSTRACT OF THE DISCLOSURE A process is provided for the heat treatment of rod utilizing rolling heat by the steps of reeling the rod, after it has passed through a rod mill, into an intermediate container and heat treating the rod by paying it out from the intermediate container, running it through a heat treating line and recoiling it.

This invention relates to methods of treatment of hot rolled rod and particularly to the heat treatment of hot rolled rod by utilizing the rolling heat. Heat treatment of rod is generally considered necessary to obtain better cold working properties. The heat treating process of concern in this application consists of rapidly cooling (quenching) the rod from quenching temperature (750 C. to 900 C. depending on steel composition) to approximately 500 C. and to maintain the temperature of approximately 500 C. in the rod until all austenite is converted into sorbite (ferritic-perlitic structure). The subsequent cooling rate to room temperature is inconsequential and influences the cold working properties of the rod only when the conversion of the structure is incomplete.

A process of treating rod is known, where the heat treatment is accomplished with a lead bath. In this process, the rod is coiled after rolling and allowed to cool to room temperature for intermediate storage. For heat treatment the coils are put on a spool and reheated to quenching temperature. The rod then is run through a lead bath of approximately 550 C, for quenching and maintenance of temperature and subsequently cooling to room temperature and recoiling. The lead process has the advantage of being independent of the rolling mill and of leaving the possibility of much lower speeds for heat treatment than is possible at mill speed. The heat treatment can be accomplished with relatively simple and low cost installation; however, the processing cost is high because the rolling heat in the rod right after rolling cannot be utilized and additional heat is required to reheat the rod.

A process of treating rod is also known, where the rod is coiled or looped onto a conveyor where it is possible to blow air or spray water on it or a combination of both to quench it to 500 C. at which temperature the conversion occurs. The advantage of this process is continuity and utilization of rolling heat; however, rod comes from the rolling mill at varying temperatures and structure variations in the rod result from quenching the rod from different temperatures within one coil. The disadvantage of the process becomes moresevere the larger the rod coils are, due to the necessarily larger temperature differential between front and tail-end of the coil. The tail-end is exposed much longer to the room air, thus losing more heat. To eliminate the large temperature differential between front and tail-end for quenching purposes, and to obtain a predetermined ideal quenching temperature (which is not necessarily the front or tail-end temperature of the rod as rolled) is a necessary condition to permit rolling of much larger coils than are presently being produced.

The present invention is a process for the heat treatment of rod. In this process, the rod is run from the mill ice into an intermediate reel or other intermediate container, where the rod is stored for a short period of time until the temperature has fully equalized. During the storage period in the intermediate container, heat can be added or removed by external means, for example induction or resistance heating or air or water cooling, so that an ideal quenching temperature is obtained. To prevent scaling, the atmosphere in the intermediate container can be controlled for example by filling it with inert gas.

After the desired rod temperatures are obtained, the rod is recoiled from the intermediate reel or container on another reel. During recoiling the heat treatment of the rod and other possible treatments, for example oiling, plastic coating, etc. are performed. In the heat treatment stage for example, the now uniformly heated rod is quenched to 500 C., held at that temperature until the desired metallurgical structure is obtained and then continuously passed on to be coiled or further processed in the same continuous line and coiled. If for the heat treating of rod, the rolling heat is used, only the process where the rod is stored in an intermediate container for temperature equalization or heat addition or removal guarantees a uniform product and makes it possible to process much larger rod coils than was possible in the past.

To fully utilize the possibilities of this invention, it is advantageous to install a number of intermediate reels or containers at the exit of the rolling mill. With this arrangement, the rod can be put into the containers at the very high mill speed and removed for further processing at a much lower speed. The necessary removal speed depends on the number of intermediate containers installed. If, for example, 6 containers are installed, the pattern could be as follows:

'One container would receive rod from the mill at mill speed.

Three containers would pay out previously received coils at /3 mill speed.

One container would hold the last received coil for equalization.

One container would be empty and ready to receive the next coil from the mill.

Depending on time requirements, of course, other patterns are possible. As a general statement, it can be said that the more intermediate containers that are installed, the slower the possible pay-out speed of the containers, and the shorter the subsequent processing line.

For a practical installation, it is possible to use a variety of known and presently manufactured equipment. The process involves mostly the arrangement and special adaptation of the known components. Only the intermediate reel or container requires a new approach and is herefore a part of this invention.

The storage reel or container is lined with insulating material. Depending on the circumstances of a particular installation, the reel or container can be equipped with heating facilities for preheating the container and heating the rod. Air blowing equipment or water-cooling can be installed and facilities for maintaining an inert gas atmosphere can be connected.

In the foregoing general description, I have set out certain objects, purposes and advantages of my invention. Other objects, purposes and advantages of my invention will be apparent from the following description and the accompanying drawings in which:

FIGURE 1 shows a schematic arrangement for the process of this invention; and

FIGURE 2 shoWs a vertical fragmentary section of an intermediate storage reel.

Referring to the drawings, I have illustrated a plant consisting of a rod finishing mill 1, a distributor 6, guides 2 to the intermediate reels 3, the heat treating and processing equipment 4 and reels 5. In the particular schematic arrangement shown in FIGURE 1, rod is received by reel 3a from mill 1. Reels 3b, 3c, 3d and 3e are paying out through processing equipment 4 (working parallel) to reels 5b, 5c, 5d, 5e. Reels 3 5a and 5f are waiting to receive rod.

In FIGURE 2, I have illustrated a form of intermediate storage reel. The reel has a completely closed steel shell 7 and is lined with insulation 8. Inside is a cone 9 which deflects the rod which enters through opening 10 so that it is deposited around the cone 9. The reel container is rigidly connected to shaft 11 by gussets 12. Shaft 11 can rotate in stationary bearings (not shown). The rod enters through guide tube 13 into the interior of steel shell 7 and can be removed through the same tube.

I claim:

1. A process for the heat treatment of rod, where the rolling heat is utilized comprising the steps of reeling the rod after the rod has passed through a rod mill into an intermediate container for temperature equalization and heat treating the rod by paying it out from the intermediate container, running it through the heat treating line and recoiling it.

2. A process according to claim 1 where the payout speed from the intermediate storage container is a frac- .4 tion of the rod mill speed and a plurality of containers and reels are provided receiving the rod.

3. A process according to claim 1 where the intermediate storage container can be filled with a controlled atmosphere and heated by external means.

4. A process according to claim 1 wherein after heat treating but before recoiling the rod is cooled sufiiciently to permit further processing, and where further processing is applied in one continuous operation.

References Cited UNITED STATES PATENTS 351,838 11/1886 LenoX 72424 X 2,019,445 10/1935 Crapo 148-453 X 2,023,736 12/1935 Lloyd 148l53 X 2,049,053 7/ 1936 Evans 72-424 X 2,300,329 10/1942 Wood et a1 148-153 3,276,920 10/1966 Sims 148-153 RICHARD O. DEAN, Primary Examiner US. Cl. X.R. 148-155 

